This invention relates to processes for the extraction of copper from copper ores, and to compounds useful in such processes.
In the extraction of copper from copper ores, various reagents have been used for the extraction, including ketoximes, aldoximes, mixtures of ketoximes and aldoximes, and certain alcohols and esters.
The present invention relates to an improved process for the preparation of ketoximes, to the ketoximes prepared by the process, to mixtures comprising the ketoximes and aldoximes, and to a process for extracting copper metal from copper ores using the mixtures of ketoximes and aldoximes.
Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions used herein are to be understood as modified in all instances by the term xe2x80x9caboutxe2x80x9d.
One embodiment of the improved process of the invention for the preparation of ketoximes comprises the following steps:
A) heating at least one phenol ester containing unreacted phenols in an inert organic solvent with a Lewis acid and a monocarboxylic acid halide (preferably chlorine or bromine) or anhydride to obtain a ketone by the Fries Rearrangement;
B) isolating the ketone reaction product from the reaction mixture; and
C) reacting hydroxylamine or a salt thereof with the ketone obtained in step B) to produce a ketoxime from said ketone.
While the above process will work with various phenol esters, it is preferred that in step A) the at least one phenol ester has the formula I or II below: 
in which R is an alkyl group having from 1 to 25 carbon atoms, an ethylenically unsaturated aliphatic group containing from 3 to 25 carbon atoms, or xe2x80x94OR1 where R1 is an alkyl group or ethylenically unsaturated aliphatic group as defined above, and R2 is an alkyl group containing 1 to 25 carbon atoms or an ethylenically unsaturated aliphatic group containing 3 to 25 carbon atoms; with the proviso that the total number of carbon atoms in the R and R2 groups is from 3 to 25. 
in which R has the same meaning as in formula I; n is 0 or 1; and R3 is an alkyl group having from 1 to 25 carbon atoms, an ethylenically unsaturated aliphatic group containing from 3 to 25 carbon atoms, or xe2x80x94OR1 wherein R1 is an alkyl group or ethylenically unsaturated aliphatic group as defined above, with the proviso that the total number of carbon atoms in the R and R3 groups is from 3 to 25.
The above phenol esters can be readily obtained from the corresponding phenols by methods well known to the art.
The organic solvent is any organic solvent or mixture of solvents which is immiscible with water and inert to the water, to the Lewis acid catalyst, and to the monocarboxylic acid halide or anhydride, e.g. aliphatic and aromatic hydrocarbons, chlorinated hydrocarbons, esters and ethers. Toluene is preferred.
The Lewis acid is preferably aluminum chloride, although other Lewis acids can also be used, such as boron trifluoride. The quantity of Lewis acid can range from 0.9 to 1.5 moles per mole of phenol ester.
While various monocarboxylic acid halides and anhydrides can be used in the present process, the monocarboxylic acid halide or anhydride is preferably selected from compounds of formula III or IV below: 
where R2 is an alkyl group containing 1 to 25 carbon atoms or an ethylenically unsaturated aliphatic group containing 3 to 25 carbon atoms, with the proviso that the total number of carbon atoms in the R group in formula I plus the R2 group in formula III is from 3 to 25; and x is halogen or 
where R3 is an alkyl group having from 1 to 25 carbon atoms, an ethylenically unsaturated aliphatic group containing from 3 to 25 carbon atoms, or xe2x80x94OR1 where R1 is an alkyl group or ethylenically unsaturated aliphatic group as defined above; n is 0 or 1; and y is halogen or 
with the proviso that the total number of carbon atoms in the R group in formula II plus the R3 group in formula IV is from 3 to 25.
The R2 or R3 groups in the monocarboxylic acid halide or anhydride can be the same as the R2 or R3 groups in the esters of formulae I and II, or can be different therefrom, but are preferably the same.
The reaction temperature in step A) can range from 50xc2x0 to 150xc2x0 C., preferably from 100 to 125xc2x0 C., and more preferably at the reflux temperature of the mixture.
The mixture is preferably heated for a time period in the range of from 2 to 6 hours.
It is also preferred to add the Lewis acid and monocarboxylic acid halide or anhydride by slow addition during the entire reaction period or during at least a major portion thereof.
It is also preferred to maintain the reaction mixture at the reaction temperature for an additional period (holding period) of from 1 to 4 hours.
For every mole of phenol ester, from 0.5 to 2 moles, preferably from 0.9 to 1.1 moles of Lewis acid is present, and from 0.1 to 1 mole, preferably from 0.2 to 0.6 moles of monocarboxylic acid halide or anhydride is present. The above ranges are however not critical and quantities of components outside these ranges can be employed.
Step B) can be carried out in any convenient manner such as by washing the reaction mixture with water to remove the Lewis acid, and then distilling off the inert organic solvent, followed by distillation to obtain a substantially pure ketone.
Step C) is carried out by heating the mixture to a temperature between 20xc2x0 and 90xc2x0 C. until the reaction is substantially complete.
The hydroxylamine or salt thereof is added in approximately molar proportions based on the quantity of ketone reaction product isolated in step B).
Hydroxylamine itself or a salt thereof, such as the sulfate salt, can be used in step C).
The reaction in step C) is preferably carried out in a solvent such as aqueous ethanol or toulene. When a salt of hydroxylamine is used, a base such as sodium carbonate or sodium or potassium hydroxide is added in a quantity sufficient to liberate hydroxylamine.
When the reaction is completed, usually after a few hours, the reaction mixture is neutralized if needed with a mineral acid, and the ketoxime product extracted with a water-immiscible solvent, e.g. chloroform toluene, or kerosene, or if a solid, collected by filtration.
A second embodiment of the improved process of the invention for the preparation of ketoximes comprises the following steps:
A) reacting a phenol with a monocarboxylic acid, acid halide, or acid anhydride in an inert organic solvent in the presence of an acid catalyst to esterify the phenol;
B) removing any water of reaction either during step A or in a separate step following step A);
C) adding a Lewis acid to the resulting anhydrous reaction mixture;
D) reacting the reaction mixture from step C) to a reaction temperature and for a time to convert most of the esterified phenol to a ketone by the Fries Rearrangement;
E) maintaining the reaction for an additional time period of from 2 to 10 hours at the reaction temperature;
F) at a time of from half to three-quarters of said additional time period adding to the heated reaction mixture additional aliphatic monocarboxylic acid, acid halide or acid anhydride, optionally with additional Lewis acid, and continuing to maintain the heated reaction mixture at the reaction temperature for the remainder of said additional time period;
G) isolating the ketone reaction product from the reaction mixture; and
H) reacting hydroxylamine or a salt thereof with the ketone obtained in step G) to produce a ketoxime from said ketone.
In step A) the phenol has the formula: 
where R is an alkyl group having from 1 to 25 carbon atoms, an ethylenically unsaturated aliphatic group containing from 3 to 25 carbon atoms, or an xe2x80x94OR1 group where R1 is an alkyl group or ethylenically unsaturated aliphatic group as defined above.
The monocarboxylic acid, acid halide, or acid anhydride is selected from a compound of formula VI or formula VII below: 
where R2is an alkyl group containing 1 to 25 carbon atoms or an ethylenically unsaturated aliphatic group containing 3 to 25 carbon atoms, with the proviso that the total number of carbon atoms in the R group in formula VI plus the R3 group in formula VII is from 3 to 25; and x is xe2x80x94OH, halogen (preferably chlorine or bromine), or 
is where R3 is an alkyl, group having from 1 to 25 carbon atoms, an ethylenically unsaturated aliphatic group containing from 3 to 25 carbon atoms, or xe2x80x94OR1 where R1 is an alkyl group or ethylenically unsaturated aliphatic group as defined above; n is 0 or 1; and y is OH, halogen (preferably chlorine or bromine), or 
with the proviso that the total number of carbon atoms in the R group in formula V plus the R3 group in formula VII is from 3 to 25.
The organic solvent is any organic solvent or mixture of solvents which is immiscible with water and inert to the water, to the acid catalyst, to the phenol, and to the monocarboxylic acid, acid halide, or acid anhydride, e.g. aliphatic and aromatic hydrocarbons, chlorinated hydrocarbons, esters, and ethers. Toluene is preferred.
The acid catalyst is preferably a sulfonic acid, e.g. methane or p-toluene sulfonic acid. However, other acid catalysts can be used such as a mineral acid, e.g. sulfuric acid, hydrochloric acid, and the like. The catalyst can be present in from 0.1 to 5% by weight, based on the weight of the reactants.
Step A) can be carried out at a temperature of from 30xc2x0 C. to the boiling point of the organic solvent. Where an organic solvent is used which will azeotrope water, any water of reaction present can be removed as formed. Water of reaction will form when a monocarboxylic acid is used as a reactant.
Preferably, approximately equimolar quantities of reactants are used in step A).
Step B), if needed, can be carried out by heating the reaction mixture until any water present has distilled off.
In step C) the Lewis acid is preferably aluminum chloride, although other Lewis acids can also be used, such as boron trifluoride. The quantity of Lewis acid can range from 0.9 to 1.5 moles per mole of ester formed in step A).
In step D) the reaction temperature can range from 30xc2x0 C. to 150xc2x0 C., preferably from 50xc2x0 C. to 125xc2x0 C., and more preferably at the reflux temperature of the mixture.
In step F) the additional monocarboxylic acid or derivative thereof and optional Lewis acid is added when the additional time period is from one-half to three-quarters over, e.g. if the additional time period used is 4 hours, then the addition is made during the period of from 2 to 3 hours.
The quantity of additional monocarboxylic acid or derivative thereof can range from 10% to 50% by weight of the quantity present in step A). The quantity of additional Lewis acid, if also added, can range from 1% to 10% of the quantity present in step A).
Steps G) and H) are carried out in the same manner as steps B) and C) in the first embodiment.
A third embodiment of the process of the invention comprises the steps of:
A) reacting a phenol with a monocarboxylic acid halide or anhydride in an inert organic solvent in the presence of a Lewis acid (preferably AlCl3 or BF3) at a temperature and for a time sufficient to esterify the phenol and rearrange the esterified phenol to a ketone;
B) maintaining the heated reaction mixture for an additional time period of from 2 to 10 hours at the reaction temperature;
C) at a time of from half to three-quarters of said additional time period, adding to the heated reaction mixture additional aliphatic monocarboxylic acid or acid halide, optionally with additional Lewis acid, and continuing to maintain the heated reaction mixture at the reaction temperature for the remainder of said additional time period;
D) isolating the ketone reaction product from the reaction mixture; and
E) reacting hydroxylamine or a salt thereof with the ketone obtained in step D) to produce a ketoxime from said ketone.
In the above reaction sequence, the phenol, monocarboxylic acid halide or anhydride and the inert organic solvent are the same as those used in the second process embodiment. Also, steps C) through E) are carried out in the same manner as steps F) through H) of the second embodiment.
The reaction temperature in step A) is from 20xc2x0 C. to 90xc2x0 C.
The ketone intermediate products produced by the above process embodiments have the following formulae: 
wherein R and R2 have the meaning given above, or 
wherein R, R3 and n have the meanings given above.
The ketoximes obtained in step C) of the first embodiment, step H) of the second embodiment, and step E) of the third embodiment are the oximes obtained from the above ketones, i.e. ketoximes of the formula: 
The ketones obtained from prior known processes contain a relatively large quantity of unreacted phenols used as starting materials in the preparation of the phenol esters. These unreacted phenols are extremely difficult to separate from the ketone product. Prior processes produce ketones containing 10% by weight or more of unreacted phenols.
The-present process results in ketone intermediates containing less than 10%, usually less than 8%, often less than 6%, and even less than 3% by weight of unreacted phenols.
Moreover, the ketoxime products resulting from the oximation of the ketones similarly contain less than 10%, usually less than 8%, often less than 6%, and even less than 3% by weight of unreacted phenols. Hence, the ketoxime products obtained by the processes of the invention have a significantly higher degree of purity than those produced by prior art processes.
In addition, the product yields of ketones and ketoximes are significantly higher than yields obtained by known processes, e.g. a 10% higher yield, since a significant portion of unreacted phenols in the phenol ester starting material is converted to the desired ketone product.
Another advantage lies in the use of the present ketoxime products in the extraction of copper from copper ores, since there is less copper in the raffinate, and hence a higher recovery of copper from the ore.
This invention also relates to reagent compositions useful in the extraction of copper from copper ores, comprising at least one ketoxime of the invention and at least one aldoxime, optionally with one or more of equilibrium modifiers, kinetic active substances, and liquid diluents.
Preferred ketoximes for use in the present compositions are those of formula X above having an isomeric mixture of 7 to 12 carbon alkyl groups as a single substituent on the ring para to the hydroxyl group. Also preferred are compounds wherein the R2 alkyl group is methyl. Consequently, illustrative of preferred phenyl alkyl ketone oxime compounds is 2-hydroxy-5-nonyl phenyl methyl ketone oxime.
Also preferred are benzophenone oxime compounds of Formula Xl having a single alkyl ring substituent having from 7 to 12 carbon atoms in a position para to the hydroxyl group, which alkyl substituent is a mixture of isomers. Examples of such compounds are 2-hydroxyl-5-nonyl benzophenone oxime and 2-hydroxy-5-dodecyl benzophenone oxime which are obtained as mixtures of alkyl isomeric forms when commercial nonylphenol and dodecyl phenol are respectively employed in their synthesis. Preferred phenyl benzyl ketone oximes of Formula (XI) like the above-noted benzophenone oximes, are those having an isomeric mixture of 7 to 12 carbon alkyl groups as a single substituent on the ring para to the hydroxyl group. These preferred compounds are exemplified by the compound, 2-hydroxy-5-nonylphenyl benzyl ketone oxime, as manufactured from a commercial nonylphenol comprising a mixture of nonyl isomeric forms.
The aldoximes useful in the present compositions are those of formula XII below: 
in which R is as defined above with respect to Formulas I and II, c has a value of 1, 2, 3 or 4, and the total number of carbon atoms in Rc is from 3 to 25. Preferred compounds of Formula XII are those wherein c is 1, R is a straight or branched chain alkyl group having from 7 to 12 carbon atoms, and wherein R is attached in a position para to the hydroxyl group. Among these, the more preferred are those wherein R is a mixture of isomers.
Compounds of Formula XII (i.e., hydroxy benzaldoxime compounds, sometimes referred to as xe2x80x9csalicylaldoximesxe2x80x9d) may suitably be prepared according to the methods described in Ackerley, et al., U.S. Pat. No. 4,020,105 or Ackerley, et al., U.S. Pat. No. 4,020,106 or by oximation of aldehydes prepared according to Beswick, U.S. Pat. No. 4,085,146. The above patents are incorporated herein by reference. Again, preferred compounds are those having an isomeric mixture of 7 to 12 carbon alkyl groups as a single substituent para to the hydroxyl group. Mixed alkyl isomeric forms of 2-hydroxy-5-heptyl benzaldoxime, 2-hydroxy-5-octyl benzaldoxime, 2-hydroxy-5-nonyl benzaldoxime and 2-hydroxy-5-dodecyl benzaldoxime are thus preferred.
Compositions of the invention comprise mixtures of one or more ketoximes of Formulas X and XI with one or more aldoximes of Formula XII in molar ratios ranging from 1:100 to 100:1 and preferably from 1:4 to 4:1 with good results being obtained at ratios of 1:1.
Kinetic additive substances may be present in amounts ranging from 0 to 20 mole percent based on ketoxime content and preferably from 0 to 5 mole percent. If present at all, as little as 0.01 mole percent may be used. Preferred kinetic additives include xe2x88x9d-hydroxy oximes described in Swanson, U.S. Pat. No. 3,224,873 and xe2x88x9d, xcex2-dioximes described in Koenders, et al., U.S. Pat. No. 4,173,616. The above patents are incorporated herein by reference. A preferred xe2x88x9d-hydroxy oxime kinetic additive is 5,8-diethyl-7-hydroxydodecan-6-oxime and a preferred dioxime kinetic additive is a mixture of 1-(4xe2x80x2-alkylphenyl)-1,2-propanedione dioximes according to Example 3 of U.S. Pat. No. 4,173,616.
A particularly preferred composition of the invention is a mixture of from 25 to 75 mole % of 2-hydroxy-5-nonylacetophenone oxime prepared by a process of the invention and from 75 to 25 mole % of 5-dodecylsolicylaldoxime.
Equilibrium modifier substances may be incorporated in the formulations of the invention in amounts providing a degree of modification of the hydroxyl aryl aldoxime constituent, in the absence of any hydroxy aryl ketoxime, of from about 0.4 to 1.0 and most preferably from about 0.55 to 1.0. Equilibrium modifiers suitable for use in the present invention include; but are not limited to, long chain (preferably C6-C20) aliphatic alcohols such as n-hexanol, n-octanol, 2-ethylhexanol, isodecanol, dodecanol, tridecanol, hexadecanol, and octadecanol; long chain alkylphenols such as heptylphenol, octylphenol, nonlyphenol and dodecylphenol; organophosphorus compounds such as triloweralkyl (C4 to C8) phosphates, especially, tributyl phosphate and tri(2-ethylhexyl)phosphate; and either saturated or unsaturated aliphatic or aromatic-aliphatic esters containing from 10 to 30 carbon atoms. The esters may be polyesters, especially diesters. The esters are preferably highly branched. Optionally the esters may contain other functional groups, more particularly a hydroxyl group.
In the context of this invention xe2x80x98highly branchedxe2x80x99 means that the ratio of the number of methyl carbons to non methyl carbons is higher than 1:5.
Especially useful in these compositions and processes are esters derived from certain diacids, preferably branched diacids. Examples include 2,2,4-trimethyl-1,3-pentanediol diisobutyrate and the benzoic acid ester of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate. The latter esters are commercially available.
The optional diluents include an aliphatic, or aromatic, or mixed aliphatic/aromatic liquid hydrocarbon diluent, especially of the kerosene type commonly employed in solvent extraction processing. Incorporation of a diluent frequently aids the transport and handling of the compositions which may be highly viscous.
The above compositions can be used for extracting copper values from aqueous solutions of copper salts.
The starting material for large scale solvent extraction processing of copper is an aqueous leach solution obtained from a body of ore which contains a mixture of metals in addition to copper. The leaching medium dissolves salts of copper and other metals as it trickles through the ore, to provide an aqueous solution of the mixture of metal values. The metal values are usually leached with sulfuric acid medium, providing an acidic aqueous solution, but can also be leached by ammonia to provide a basic aqueous solution.
The aqueous solution is mixed in tanks with an extraction reagent which is dissolved in an organic solvent, e.g., a kerosene. The reagent includes an extractant chemical which selectively forms metal-extractant complex with. the copper ions in preference to ions of other metals. The step of forming the complex is called the extraction or loading stage of the solvent extraction process.
The outlet of the mixer continuously feeds to a large settling tank, where the organic solvent (organic phase), now containing the copper-extractant complex in solution, is separated from the depleted aqueous solution (aqueous phase). This part of the process is called phase separation. Usually, the process of extraction is repeated through two or more mixer/settler stages, in order to more completely extract the desired metal.
After extraction, the depleted aqueous feedstock (raffinate) is either discharged or recirculated to the ore body for further leaching. The loaded organic phase containing the dissolved copper-extractant complex is fed to another set of mixer tanks, where it is mixed with an aqueous strip solution of concentrated sulfuric acid. The highly acid strip solution breaks apart the copper-extractant complex and permits the purified and concentrated copper to pass to the strip aqueous phase. As in the extraction process described above, the mixture is fed to another settler tank for phase separation. This process of breaking the copper-extractant complex is called the stripping stage, and the stripping operation is repeated through two or more mixer-settler stages to more completely strip the copper from the organic phase.
From the stripping settler tank, the regenerated stripped organic phase is recycled to the extraction mixers to begin extraction again, and the strip aqueous phase is customarily fed to an electrowinning tankhouse, where the copper metal values are deposited on plates by a process of electrodeposition. After electrowinning the copper values from the aqueous solution, the solution, known as spent electrolyte, is returned to the stripping mixers to begin stripping again.
In the above process, the extraction reagent is a composition of the invention described above, dissolved in an organic solvent such as a kerosene, i.e. the compositions of the invention can be formulated with an organic solvent, or an organic solvent can be added to the composition prior to use in the above copper extraction process.
The amount of composition used to extract copper from the aqueous leach solution will depend on the concentration of metal salts in the leach solution. For use with aqueous leach solutions containing 1 g. or more per liter of metal, it is preferred to use from 20 to 200 g. of the oximes per liter of organic solution. Suitable relative volumes of organic to aqueous phases can be readily determined. A 1:1 ratio can be used for example.